Peptide analogs and mimetics suitable for in vivo use in the treatment of diseases associated with abnormal protein folding into amyloid, amyloid like deposits or beta sheet rich pathological precursor thereof

ABSTRACT

The present invention is an inhibitory peptide capable of inhibiting β pleated sheet formation in amyloid β-peptide. The inhibitory peptide is a βsheet breaker peptide analog designed by chemical modification of a βsheet breaker peptide capable of inhibiting β pleated sheet formation in amyloid β-peptide.  
     The present invention also includes an inhibitory peptide capable of inhibiting conformational changes in prion PrP protein associated with amyloidosis. The inhibitory peptide being a βsheet breaker peptide analog designed by chemical modification of a βsheet breaker peptide capable inhibiting the conformational changes in prior PrP protein associated with amyloidosis.  
     In addition, the present invention includes a peptide mimetic with the following structure:  
                 
 
     In another embodiment, the peptide mimetic has the following structure:  
                 
 
     In yet another embodiment, the peptide mimetic has the following structure:

[0001] This application is a Divisional of U.S. Ser. No. 09/706,540filed Nov. 4, 2000, which claims priority from U.S. ProvisionalApplication No. 60/163,911, which was filed on Nov. 5, 1999.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to peptide analogs and peptidemimetics of β sheet breaker peptides suitable for in vivo use intreating mammals with protein conformational diseases such asAlzheimer's and prion disease. More particularly, the present inventionis directed to novel peptide analogs and mimetics, pharmaceuticalcompositions containing one or a mixture of such peptide analogs andmimetics, and methods for preventing, treating, or detecting disordersor diseases associated with abnormal protein folding into amyloid oramyloid like deposits or precursors thereof having a pathologicalbeta-sheet structure.

[0004] 2. Description of Related Art

[0005] Extensive evidence has been accumulated indicating that severaldiverse disorders have the same molecular basis, i.e. a change in aprotein conformation (Thomas et al., Trends Biochem. Sci. 20: 456-459,1995; Soto, J. Mol. Med. 77: 412-418, 1999). These proteinconformational diseases include Alzheimer's disease, prion-relateddisorders, systemic amyloidosis, serpin-deficiency disorders,Huntington's disease and Amyotrophic Lateral Sclerosis (Soto 1999,supra). The hallmark event in protein conformational disorders is achange in the secondary and tertiary structure of a normal proteinwithout alteration of the primary structure. The conformationallymodified protein may be implicated in the disease by direct toxicactivity, by the lack of biological function of normally folded protein,or by improper trafficking (Thomas et al., 1995, supra). In the caseswhere the protein is toxic, it usually self-associates and becomesdeposited as amyloid fibrils in diverse organs, inducing tissue damage(Thomas et al., 1995, supra; Kelly, Curr. Opin. Struct. Biol. 6: 11-17,1996; Soto, 1999, supra).

[0006] Alzheimer's disease (AD) is a devastating neurodegenerativeproblem characterized by loss of short term memory, disorientation, andimpairment of judgment and reasoning. AD is the most common dementia inelderly population. It is estimated that more than twenty five millionpeople worldwide are affected in some degree by AD (Teplow, Amyloid 5:121 142, 1998). A hallmark event in AD is the deposition of insolubleprotein aggregates, known as amyloid, in brain parenchyma and cerebralvessel walls. The main component of amyloid is a 4.3 KDa hydrophobicpeptide, named amyloid beta peptide (Aβ) that is encoded on thechromosome 21 as part of a much longer precursor protein (APP) (Selkoe,Science 275: 630-631, 1997). Genetic, biochemical, and neuropathologicalevidence accumulated in the last 10 years strongly suggest that amyloidplays an important role in early pathogenesis of AD and perhaps triggersthe disease (Soto et al., J. Neurochem. 63: 1191-1198, 1994; Selkoe,1997, supra; Teplow, 1998, supra; Sisodia and Price, FASEB J. 9:366-370, 1995; Soto, Mol. Med. Today 5: 343 350, 1999).

[0007] Amyloid is a generic term that describes fibrillar aggregatesthat have a common structural motif, i.e., the (3 pleated sheetconformation (Serpell et al., Cell Mol. Life Sci. 53: 887, 1997; Sipe,Ann. Rev. Biochem. 61: 947-975, 1992). These aggregates exhibit specifictinctorial properties, including the ability to emit a greenbirefringent glow after staining with Congo red, and the capacity tobind the fluorochrome, thioflavin S (Sipe, 1992, supra; Ghiso et al.,Mol. Neurobiol. 8: 49 64, 1994). There are more than a dozen humandiseases of different etiology characterized by the extracellulardeposition of amyloid in diverse tissues, which lead to cell damage,organ dysfunction, and death. Among the diseases involving amyloidosis,it is possible to highlight Alzheimer's disease, prion related disorders(also known as transmissible spongiform encephalopathy), and systemicamyloidosis (Table 1). The amyloid fibrils are usually composed ofproteolytic fragments of normal or mutant gene products. There are over16 different proteins (Table 1) involved in amyloid deposition indistinct tissues (Ghiso et al., 1994, supra).

[0008] The formation of amyloid is basically a problem of proteinfolding, whereby a mainly random coil soluble peptide becomesaggregated, adopting a β-pleated sheet conformation (Kelly, 1996, supra;Soto, 1999, supra). Amyloid formation proceeds by hydrophobicinteractions among conformationally altered amyloidogenic intermediates,which become structurally organized into a β-sheet conformation uponpeptide interaction. The hydrophobicity appears to be important toinduce interaction of the monomers leading to aggregation, while theβ-sheet conformation might determine the ordering of the aggregates inamyloid fibrils. In an attempt to inhibit amyloid fibril formation,these two properties were separated by designing short syntheticpeptides bearing sequence homology and a similar degree ofhydrophobicity as the peptide domain implicated in the conformationalchange, but having a very low propensity to adopt a β-sheet conformation(called β-sheet breaker peptides) (Soto et al., 1996, supra; Soto etal., 1998, supra). The aim was to design a peptide with the ability tobind specifically to the amyloidogenic peptide forming a complex thatstabilizes the physiological conformation and destabilizes the abnormalconformation of the peptide (Soto, 1999, supra). TABLE 1 Disordersrelated with amyloidosis and the protein component of the amyloidfibrils DISEASE FIBRIL COMPONENT Alzheimer's disease Amyloid β proteinPrimary systemic amyloidosis Immunoglobulin light chain or fragmentsthereof Secondary systemic amyloidosis, Fragments of serum amyloid-AFamilial Mediterranean fever Spongiform encephalopathy Fragments ofprion protein Senile systemic amyloidosis, Transthyretin and fragmentsFamilial amyloid polyneuropathy thereof Hemodialysis related amyloidosisβ2-microglobulin Hereditary cerebral amyloid angiopathy, Cystain CIcelandic type Familial amyloidosis, Finnish type Gelsolin fragmentsType II diabetes Fragments of islet amyloid polypeptide Familial amyloidpolyneuropathy Fragments of apolipoprotein A-1 Medullar carcinoma of thethyroid Fragments of calcitonin Atrial amyloidosis Atria] natriureticfactor Hereditary non neuropathic systemic Lysozyme or fragments thereofamyloidosis Hereditary renal amyloidosis Fibrinogen fragments Isletamyloid Insulin Amyloidosis in senescence Apolipoprotein A II

[0009] β-sheet breaker peptides have so far been designed to block theconformational changes that occur in both Aβ and prion protein (PrP),which are implicated in the pathogenesis of Alzheimer's and priondisease, respectively. The prior art has previously shown that 11- and5-residue β-sheet breaker peptides (namely, iAβ1 and iAβ5, respectively)homologous to the central hydrophobic region of Aβ inhibit peptideconformational changes that result in amyloid formation and alsodissolved preformed fibrils in vitro (Soto et al., Biochem. Biophys.Res. Commun. 226: 672-680, 1996; Soto et al., Nature Med. 4: 822-826,1998). In addition, the 5-residue peptide is capable of preventing theneuronal death induced by the formation of β-sheet rich oligomeric Aβstructures in cell culture experiments (Soto et al., 1998, supra).Furthermore, by using a rat model of amyloidosis induced byintracerebral injection of Aβ 1-42, the prior art has shown thatco-injections of the 5-residue β-sheet breaker peptide decreasedcerebral Aβ accumulation and completely blocked the deposition offibrillar amyloid like lesions in the rat brain (Soto et al., 1998,supra). Finally, the β-sheet breaker peptide injected eight days afterthe injection of Aβ was able to disassemble preformed Aβ fibrils in therat brain in vivo, that leads to a reduction in the size of amyloiddeposits (Sigurdsson, E. M.; Permanne, B.; Soto, C.; Wisniewski, T.;Frangione. B; J. Neuropathol. Exp. Neurol. 2000 January; 59 (1):11-7).Interestingly, removal of amyloid by the β-sheet breaker peptide revertsthe associated cerebral histologic damage, including neuronal shrinkageand microglial activation.

[0010] β-sheet breaker peptides have also been designed to prevent andto revert conformational changes caused by prions (PrP). Based on thesame principles and using as a template the PrP sequence 114-122, theprior art has shown that when a set of β-sheet breaker peptides wassynthesized, a 13-residue peptide (iPrP13) showed the greatest activity(Soto, 1999, supra). Several in vitro cell culture and in vivo assayswere used to test for inhibitory activity and the results clearlyindicated that it is possible not only to prevent the PrP^(c)→PrP^(sc)conversion, but more interestingly to revert the infectious PrP^(sc)conformer to a biochemical and structural state similar to PrP^(c) (Sotoet al., manuscript submitted).

[0011] Short peptides have been utilized extensively as drugs inmedicine (Rao et al., C. Basava and G. M. Anantharamaiah, eds. Boston:Birkhauser, pp. 181-198, 1994). However, the development of peptidedrugs is strongly limited by their lack of oral bioavailability andtheir short duration of action resulting from enzymatic degradation invivo (Fauchere and Thurieau, Adv. Drug Res. 23: 127-159, 1992). Progressin recent years toward the production of peptide analogs (such aspseudopeptides and peptide mimetics) with lower susceptibility toproteolysis has increased the probability to obtain useful drugsstructurally related to their parent peptides (Fauchere and Thurieau,1992, supra). Improving peptide stability to proteases not onlyincreases the half-life of the compound in the circulation but alsoenhances its ability to be transported or absorbed at different levels,including intestinal absorption and blood-brain barrier permeability,because transport and absorption appear to be highly dependent upon thetime of exposure of membranes or barriers to the bioactive species(Fauchere and Thurieau, 1992, supra).

SUMMARY OF THE INVENTION

[0012] The present invention is an inhibitory peptide capable ofinhibiting β pleated sheet formation in amyloid β-peptide, theinhibitory peptide being a βsheet breaker peptide analog designed bychemical modification of a βsheet breaker peptide capable of inhibitingβ pleated sheet formation in amyloid β-peptide.

[0013] The peptide is altered chemically by: (1) modifications to the N-and C-terminal ends of the peptide; (2) changes of the side-chain, whichcan involve amino acid substitutions; (3) modification in the α-carbonincluding methylations, alkylations and dehydrogenations; (4) chiralitychanges by replacing D- for L-residue; (5) head-to-tail cyclizations;and (6) introduction of amide bond replacements, i.e. changing the atomsparticipating in the peptide (or amide) bond.

[0014] The present invention also includes an inhibitory peptide capableof inhibiting conformational changes in prion PrP protein associatedwith amyloidosis, the inhibitory peptide being a βsheet breaker peptideanalog designed by chemical modification of a βsheet breaker peptidecapable inhibiting the conformational changes in prior PrP proteinassociated with amyloidosis.

[0015] In addition, the present invention includes a peptide mimeticwith the following structure:

[0016] In another embodiment, the peptide mimetic has the followingstructure:

[0017] In yet another embodiment, the peptide mimetic has the followingstructure:

[0018] The present invention also includes a method for preventing,treating, or detecting disorders or diseases associated with abnormalprotein folding into amyloid or amyloid-like deposits or precursorsthereof having a pathological beta-sheet structure is claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a schematic representation of the peptide bond and thepotential target sites for peptide modifications.

[0020]FIG. 2 is a graph depicting the pharmacokinetics of a 11-residueβ-sheet breaker peptide inhibitor of Alzheimer's amyloidosis (Seq.RDLPFYPVPID, SEQ ID NO: 9) in its natural L-configuration and in thenon-natural D-form.

[0021]FIGS. 3A and 3B are representations of the tridimensionalstructure of Alzheimer's and prion β-sheet breaker peptides iAβ5 and iPrP13, respectively.

[0022]FIGS. 4a and 4 b are graphs showing the bioavailability andstability of iA5 and Ac-iAβ5-Am, respectively over time.

[0023]FIG. 5a provides a graphical comparison of Aβ1-40 incubated withvarious other peptides.

[0024]FIG. 5b is a graph of amyloid formation vs. the Ac-iAβ5-Amconcentration.

[0025]FIG. 5c is a graph of amyloid formation vs. the iAβ5concentration.

[0026]FIG. 6 shows a model where there is an 83% dissolution of depositsin the ventricle area and a 30% dissolution of amyloid plaque in theamygdala.

DETAILED DESCRIPTION OF THE INVENTION

[0027] In the present invention, the bioavailability and stability of aninhibitory peptide is improved by chemically modifying the parentpeptide to produce a derivative more suitable for in vivo use, which ispreferably administered orally. The inhibitory peptide is capable ofinhibiting β pleated sheet formation in an amyloid β-peptide. Moreover,the inhibitory peptide is a βsheet breaker peptide analog designed bychemical modification of a βsheet breaker peptide capable of inhibitingβ pleated sheet formation in amyloid β-peptide.

[0028] This invention also includes an inhibitory peptide capable ofinhibiting conformational changes in prion PrP protein associated withamyloidosis, where the inhibitory peptide is a βsheet breaker peptideanalog designed by chemical modification of a βsheet breaker peptide andis capable of inhibiting the conformational changes in prion PrP proteinassociated with amyloidosis.

[0029] In FIG. 1, a generalized peptide backbone is shown, wherepossible targets for chemical modification are highlighted. The possibletargets include the following: (1) modifications to the N- andC-terminal ends of the peptide (targets a and b); (2) changes of theside-chain (target c) which usually involve amino acid substitutions;(3) modification in the a-carbon (target d) including methylations,alkylations and dehydrogenations; (4) chirality changes by replacing D-for L-residue; (5) head-to-tail cyclizations; and (6) introduction ofamide bond replacements (target e), i.e. changing the atomsparticipating in the peptide (or amide) bond. The latter derivatives areknown as pseudopeptides or amide bond surrogates.

[0030] Natural peptides are usually degraded by the concerted action ofspecialized endopeptidases and unspecific exopeptidases. Endopeptidasesare often present in tissues and cellular compartments and convert thepeptide into two or more inactive fragments. Exopeptidases are generallypresent in blood and peripheral organs and carry out the degradation ofthe intact peptides or their fragments to the constituent amino acidsand hence contribute to the disappearance of the peptides from thecirculation. Exopeptidases recognize the free amino or carboxyl groupsin peptides. Therefore, modification of those groups often diminish orabolish exopeptidase degradation. Head-to-tail peptide cyclizationresults in the absence of free end-terminal groups, and hence alsominimizes cleavage by exopeptidases. On the other hand, endopeptidasesrecognize the atoms participating in the amide bond. Thus, amide bondreplacements dramatically decrease degradation by endopeptidases. Thesame usually happens with modifications to the α-carbon. Since most (ifnot all) of the exo- and endo-proteases are stereospecific,substitutions of the natural L-amino acids by the D-stereoisomers resultin a clear increase in peptide stability. Finally, peptide mimetics areusually completely resistant to proteolytic degradation and often can beadministrated orally.

[0031] β-Sheet Breaker Analogues Designed by Chemical Modifications ofthe Lead Peptides.

[0032] Starting from the 5-residue Alzheimer's inhibitor peptide (iAβ5,Seq. LPFFD—also denoted as Leu Pro Phe Phe Asp, SEQ. ID. NO. 1) and the13-residue prion inhibitor peptide (iPrP13, Seq. DAPAAPAGPAVPV—alsodenoted as Asp Ala Pro Ala Ala Pro Ala Gly Pro ala Val Pro Val, SEQ. ID.NO. 2), the modifications described below are designed. The peptidesused in the present invention are synthesized using standard protocolsas disclosed by Bergmann et al., and incorporated herein by reference.(Bergmann & Zervas, Berichte der Deutschen Chemischen Gesellschaft(1932) 65: 1192-1201).

[0033] a) N- and C-terminal modifications. N-terminal acetylation ordesamination confers protection against digestion by a number ofaminopeptidases while the presence of amides or alcohols replacing theC-terminal carboxyl group prevent splitting by severalcarboxypeptidases, including carboxypeptidases A and B. The alteredpeptide sequences including these modifications are the following, whereac is acetylation, am is amidation, des is desamination, and alc isalcoholization: Alzheimer's Inhibitors Prion Inhibitors ac-Leu Pro PhePhe Asp-am ac-Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala Val Pro Val-amdes-Leu Pro Phe Phe Asp-am des-Asp Ala Pro Ala Ala Pro Ala Gly Pro AlaVal Prc Val-am ac-Leu Pro Phe Phe Asp-alc ac-Asp Ala Pro Ala Ala Pro AlaGly Pro Ala Val Pro Val-alc des-Leu Pro Phe Phe Asp-alc des-Asp Ala ProAla Ala Pro Ala Gly Pro Ala Val Pro Val-alc

[0034] b) Side-chain changes. The presence of non-natural amino acidsusually increases peptide stability. In addition, at least one of theseamino acids (α-aminoisobutyric acid or Aib) imposes significantconstraints to model peptides diminishing their conformationalflexibility. In particular, the incorporation of Aib into β-sheet modelpeptides induces the complete disruption of this structure. The β-sheetblocking activity of Aib is comparable or even greater than the naturalresidue proline used in the peptide as a β-sheet blocker. Therefore, theintroduction of Aib is expected to enhance peptide stability andinhibitory activity at the same time.

[0035] Alzheimer's Inhibitors

[0036] Leu Aib Phe Phe Asp (SEQ. ID. NO. 3)

[0037] Prion Inhibitors

[0038] Asp Ala Aib Ala Ala Aib Ala Gly Aib Ala Val Aib Val (SEQ ID NO:4)

[0039] c) Modifications in the α-carbon. The most commonly used α-carbonmodification to improve peptide stability is α-methylation. In addition,replacement of the hydrogen atom linked to the α-carbon of Phe, Val orLeu has been shown to favor the adoption of β-bend conformation andstrongly disfavor the formation of β-pleated sheet structures. Accordingto the present invention, methylation of those residues in the inhibitorpeptides is expected to enhance stability and potency.

[0040] Alzheimer's Inhibitors

[0041] (Me)Leu Pro Phe Phe Asp

[0042] Leu Pro (Me)Phe Phe Asp

[0043] Leu Pro Phe (Me)Phe Asp

[0044] (Me)Leu Pro (Me)Phe (Me)Phe Asp

[0045] Prion inhibitors

[0046] Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala (Me)Val Pro Val

[0047] Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala Val Pro (Me)Val

[0048] Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala (Me)Val Pro (Me)Val

[0049] d) Chirality changes. Replacement of the natural L-residue by theD-enantiomers dramatically increases resistance to proteolyticdegradation. The increase in stability by introduction of D-residue hasalready been demonstrated for the 11-residue β-sheet breaker peptide(iAβI). In vivo studies showed that the peptide bearing the naturalsequence rapidly degraded in rat plasma. Indeed, approximately 90% ofiAβ1 was degraded within minutes after intravenous injection.Conversely, a derivative of iAβ1 containing all the residue in theD-form showed virtually no degradation in the plasma after injection for15 minutes. For detection, the peptide was radio-iodinated usingstandard procedures. Peptide stability was evaluated after i.v bolusinjection in rats by precipitation with trichloroacetic acid.Quantitation of the intact peptide was also done by paperchromatography. Thus, iAβ5 and iPrP13 peptides (FIGS. 3A and 3B,respectively) containing all-D residue as well as peptides containingD-residue only at the N- and C-terminal ends to prevent exopeptidasedegradation are included in the compounds of the invention. In additionto the latter, D-residue are used after each proline amino acid, sinceit has been reported that a frequent endopeptidase cleavage site isafter this residue by an enzyme known as prolylendopeptidase.Alzheimer's Inhibitors Prion Inhibitors leu pro phe phe asp asp ala proala ala pro ala gly pro ala val pro val leu Pro Phe Phe asp asp Ala ProAla Ala Pro Ala Gly Pro Ala Val Pro val leu Pro phe Phe asp asp Ala Proala Ala Pro ala Gly Pro ala Val Pro val

[0050] Amino acids written with lower case letters denote D-residue.

[0051] e) Cyclic peptides. Conformationally constrained cyclic peptidesrepresent better drug candidates than linear peptides due to theirreduced conformational flexibility and improved resistance toexopeptidase cleavage. Two alternative strategies have been used toconvert a linear sequence into a cyclic structure. One is theintroduction of cysteine residue to achieve cyclization through theformation of a disulfide bridge and the other is the side-chainattachment strategy involving resin-bound head-to-tail cyclization. Toavoid modifications of the peptide sequence the latter approach is used.β-sheet breaker peptides contain the ideal sequences for facilitatingmacrocyclization because proline, due to its ability to promote turnsand loops, is a constituent of many naturally occurring or artificiallysynthesized cyclic peptides. Alzheimer's Inhibitors Prion inhibitors

[0052] f) Pseudopeptides. Pseudopeptides or amide bond surrogates refersto peptides containing chemical modifications of some (or all) of thepeptide bonds. Amide bond replacements are usually represented byretaining the amino acid designation according to the side-chain andspecifying the changes that occur between the α-carbons, using thenomenclature known as “psi-bracket.”

[0053] For example, the term Alaψ[CH₂CH₂]Gly refers to the moietyNH₂CH(CH₃)CH₂CH₂CH₂CO₂H. Several amide bond surrogates have beendescribed in Table 2 below. TABLE 2 Some amide bond surrogates and theirproperties Surrogate Properties CH₂ Short, flexible CH₂CH₂ Flexible,hydrophobic CH═CH Rigid, hydrophobic C═C Very rigid CH₂ NH Flexible,hydrophilic COCH₂ Flexible, hydrophilic CH₂S Flexible, hydrophobicCH₂S0₂ More rigid, hydrophilic NHCO Rigid, hydrophilic

[0054] Some of them are found in naturally occurring peptide analogs(such as ψ[CHOH], ψ[CSNH], ψ[COO]) while others have been artificiallysynthesized. The introduction of amide bond surrogates not onlydecreases peptide degradation but also may significantly modify some ofthe biochemical properties of the peptides, particularly theconformational flexibility and hydrophobicity. It is likely that anincrease in conformational flexibility will be beneficial for dockingthe inhibitor to the Aβ and PrP binding sites. On the other hand, sincethe interaction between the amyloidogenic proteins and the inhibitorsseems to depend to a great extent on hydrophobic interactions, it islikely that amide bond replacement increasing hydrophobicity may enhanceaffinity and hence, potency of the inhibitors. In addition, increasedhydrophobicity could also enhance transport of the peptide acrossmembranes and thus, improve barrier permeability (blood-brain barrierand intestinal barrier). Therefore, to synthesize pseudopeptides amidebond replacement is used thereby increasing flexibility andhydrophobicity, such as ψp[CH₂CH₂] and ψ[CH₂S]. The amide bonds toreplace are those located at the end of the peptide to preventexoprotease degradation and after each of the prolines, since it hasbeen described that a frequent endopeptidase cleavage site occurs afterthis residue by an enzyme known as prolylendopeptidase. Additional amidebonds that need to be protected are determined by experimental studiesinvolving the analysis of the degradation of β-sheet breaker peptides inthe plasma and tissue.

[0055] Alzheimer's Inhibitors

[0056] Leuψ[CH₂CH₂]Proψ[CH₂CH₂]Phe Pheψ[CH₂CH2]Asp

[0057] Leuψ[CH₂S]Proψ[CH₂S]Phe Phey[CH₂S]Asp

[0058] Prion Inhibitors

[0059] Aspψ[CH₂CH₂]Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala GlyProψ[CH₂CH₂]Ala Val Proψ[CH₂CH₂]Val

[0060] Aspψ[CH₂S]Ala Proψ[CH₂S]Ala Ala Proψ[CH₂S]Ala Gly Proψ[CH₂S]AlaVal Proψ[CH₂S]Val

[0061] g) Mixture of several modifications. By taking into account thefeatures of the peptide drugs on the market or under currentdevelopment, it is clear that most of the peptides successfullystabilized against proteolysis consist of a mixture of several types ofthe above described modifications. This conclusion makes sense in thelight of the knowledge that many different enzymes are implicated inpeptide degradation. The following structures contain combinations ofdifferent types of chemical modifications:

[0062] Alzheimer's Inhibitors

[0063] Ac-Leu Proψ[CH₂CH₂]Phe Phe Asp-Am

[0064] Ac-Leu Proψ[CH₂S]Phe Phe Asp-Am

[0065] (Me)Leu Proψ[CH₂CH₂]Phe Phe Asp-Am

[0066] leu Proψ[CH₂CH₂]Phe Phe asp

[0067] leu Proψ[CH₂S]Phe Phe asp

[0068] Ac-Leu Aib Phe Phe Asp-Am

[0069] (Me)Leu Aib Phe Phe Asp-Am

[0070] Leu Proψ[CH₂CH₂]Phe Phe asp

[0071] Ac-Leu pro Phe Phe Asp-Am

[0072] Ac-Leu Proψ[CH₂CH₂]Phe phe Asp-Am

[0073] Ac-Leu Proψ[CH₂S]Phe phe Asp-Am

[0074] Ac-Leu Proψ[CH₂CH₂]Phe (Me)Phe Asp-Am

[0075] Ac-Leu Proψ[CH₂CH₂]Phe (Me)Phe asp

[0076] Ac-Leu Pro phe phe Asp-Am

[0077] Ac-Leu Pro (Me)Phe phe Asp-Am

[0078] leu Proψ[CH₂CH₂]Phe phe asp

[0079] leu Pro (Me)Phe phe asp

[0080] Ac-Leu Aib Phe phe Asp-Am

[0081] Prion Inhibitors

[0082] Ac-Asp Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala GlyProψ[CH₂CH₂]Ala Val Pro Val-Am

[0083] asp Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala Gly Proψ[CH₂CH₂]AlaVal Pro val

[0084] Ac-Asp Ala Proψ[CH₂S]Ala Ala Proψ[CH₂S]Ala Gly Proψ[CH₂S]Ala ValPro Val-Am

[0085] asp Ala Proψ[CH₂S]Ala Ala Proψ[CH₂S]Ala Gly Proψ[CH₂S]Ala Val Proval

[0086] Ac-Asp Ala Aib Ala Ala Aib Ala Gly Aib Ala Val Pro Val-Am (SEQ IDNO: 5)

[0087] Ac-Asp Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala GlyProψ[CH₂CH₂]Ala Val Pro (Me) Val

[0088] Ac-Asp Ala pro Ala Ala Proψ[CH₂CH₂]Ala Gly pro Ala Val Pro Val-Am

[0089] asp Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala Gly Proψ[CH₂CH₂]AlaVal Pro (Me) Val

[0090] asp Ala Aib Ala Ala Proψ[CH₂CH₂]Ala Gly pro Ala Val Pro (Me)Val(SEQ ID NO: 6)

[0091] asp Ala Aib Ala Ala Proψ[CH₂S]Ala Gly pro Ala Val Pro (Me) Val

[0092] asp Ala Proψ[CH₂S]Ala Ala Proψ[CH₂S]Ala Gly Proψ[CH₂S]Ala Val Pro(Me) Val

[0093] Ac-Asp Ala Aib Ala Ala Proψ[CH₂CH₂]Ala Gly Aib Ala Val Pro(Me)Val (SEQ ID NO: 7)

[0094] Ac-Asp Ala Proψ[CH₂S]Ala ala Proψ[CH₂S]Ala gly Proψ[CH₂S]Ala(Me)Val Pro Val-Am

[0095] Ac-Asp Ala Aib ala Ala Proψ[CH₂CH₂]Ala Gly pro Ala Val Pro (Me)Val

[0096] asp Ala Aib Ala Ala Proψ[CH₂CH₂]Ala Gly Aib ala Val Pro Val-Am

[0097] Ac-Asp Ala pro Ala Ala Proψ[CH₂CH₂]Ala gly pro Ala (Me)Val ProVal-Am

[0098] asp Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala gly Proψ[CH₂CH₂]Alaval Pro val

[0099] Ac-Asp Ala pro Ala ala Aib Ala gly pro Ala (Me)Val Pro Val-Am(SEQ. ID. NO. 8)

[0100] Asp Ala pro Ala Ala Proψ[CH₂CH₂] Ala Gly pro Ala Val Pro Val

[0101] Asp Ala Aib Ala Ala Proψ[CH₂CH₂] Ala Gly Aib Ala (Me) Val Pro Val

[0102] Another approach to improve stability, which also may result inthe generation of orally active compounds, is to produce a peptidemimetic. A peptide mimetic is a molecule that mimics the biologicalactivity of the peptides, but is no longer a peptide in chemical nature.The term peptide mimetic has been used sometimes to describe moleculesthat are partially peptide in nature, such as pseudopeptides,semi-peptides or peptoids, but a strict definition and the one that isused in the present application is an organic molecule that no longercontains any peptide bonds. Peptide mimetics are not derivatives of aparent peptide, but rather are chemically synthesized de novo trying tomimic the structural and functional properties of the peptide. Therational design of peptide mimetics requires a sufficient knowledge ofthe pharmacophoric groups that are responsible for the activity anddetailed structural information of the peptide. The objective is toreconstruct the spatial position of the pharmaco-active groups using anorganic template to mount them. Selection of the template is importantand has to take into consideration the size and flexibility based on theconformational model of the peptide.

[0103] Peptide Mimetics Designed to Imitate Q-Sheet Breaker PeptideProperties.

[0104] The rational design of peptide mimetics requires a sufficientknowledge of the chemical groups that are responsible for the activityand detailed structural information of the peptide. The objective is toreconstruct the position of the pharmaco-active groups using an organictemplate to mount them. Selection of the template is important and hasto take into consideration the size and flexibility based on theconformational model of the peptide. From the study of the activity ofdifferent β-sheet breaker sequences bearing single amino acidsubstitutions, the residues that are key for inhibition have beendetermined. In addition, the tridimensional structure of the leadAlzheimer's and prion β-sheet breaker peptides (FIGS. 3A and 3B) wereeither modeled or experimentally determined. The 5-residue inhibitor ofAβ fibrillogenesis was modeled by energy minimization and Monte Carlosimulations using the computer program ICM. The structure of the13-residue inhibitor of prion protein conformational changes wasexperimentally calculated by 2D-NMR.

[0105] There are numerous approaches to the design and synthesis ofpeptide mimetics as described in recent reviews by Joachim Gante andIwao Ojima et al. of which are incorporated herein by reference.

[0106] The peptide mimetics shown below represent a further aspect ofthis invention.

[0107] Alzheimer's Inhibitors

[0108] Prion Inhibitors

[0109] The latter (PMiPrP5) is a shorter and easier to synthesizeversion that contains the chemically active groups and is analog to a5-residue prion β-sheet breaker peptide.

[0110] As a method of preventing or treating a disorder or diseaseassociated with amyloid or amyloid-like deposits or pathologicalbeta-sheet-rich precursors thereof, the compound of the presentinvention is administered in an effective amount to a subject in needthereof, where the subject can be human or animal. Likewise, a method ofdetecting such disorders or diseases also includes administering asufficient amount of the designed compound to visualize its binding tofibril deposits or precursors thereof by well-known imaging 15techniques.

[0111] As used herein, the term “prevention” of a condition, such asAlzheimer's disease or other amyloidosis disorders, in a subjectinvolves administering the compound according to the present inventionprior to the clinical onset of the disease. “Treatment” involvesadministration of the protective compound after the clinical onset ofthe disease. For example, successful administration of the compound ofthe present invention, after development of a disorder or diseasecomprises “treatment” of the disease. The invention is useful in thetreatment of humans as well as for veterinary uses in animals.

[0112] The compound of the present invention may be administered by anymeans that achieves its intended purpose, preferably oral. For example,administration may be by a number of different parenteral routesincluding, but not limited to, subcutaneous, intravenous, intradermal,intramuscular, intraperitoneal, intracerebral, intranasal, oral,transdermal, or buccal routes. Parenteral administration can be bolusinjection or by gradual perfusion over time.

[0113] A typical regimen for preventing, suppressing, or treating acondition associated with amyloid or amyloid-like deposits, compriseseither: (1) administration of an effective amount in one or two doses ofa high concentration of the compound in the range of 0.5 to 10 mg, morepreferably 0.5 to 5 mg, or (2) administration of an effective amount ofthe compound administered in multiple doses of lower concentrations inthe range of 10-10,000 μg, more preferably 50-500 μg over a period oftime up to and including several months to several years.

[0114] It is understood that the dosage administered will be dependentupon the age, sex, health, and weight of the recipient, kind ofconcurrent treatment, if any, frequency of treatment, and the nature ofthe effect desired. The total dose required for each treatment may beadministered by multiple doses or in a single dose. By “effectiveamount,” it is meant a concentration of the compound which is capable ofslowing down or inhibiting the 5 formation of amyloid or amyloid-likedeposits, or pathological beta-sheet precursors thereof, or ofdissolving preformed fibril deposits. Such concentrations can beroutinely determined by those of skill in the art. It will also beappreciated by those of skill in the art that the dosage may bedependent on the stability of the administered compound. A less stablecompound may required administration in multiple doses.

[0115] Preparations for parenteral administration include sterileaqueous or non-aqueous solutions, suspensions, and emulsions, which maycontain auxiliary agents or excipients which are known in the art.Pharmaceutical compositions such as tablets and capsules can also beprepared according to routine methods.

[0116] Pharmaceutical compositions comprising the compound of theinvention include all compositions wherein the compound is contained inan amount effective to achieve its intended purpose. In addition, thepharmaceutical compositions may contain suitable pharmaceuticallyacceptable carriers comprising excipients and auxiliaries whichfacilitate processing of the active compounds into preparations whichcan be used pharmaceutically. Suitable pharmaceutically acceptablevehicles are well known in the art and are described for example inGennaro, Alfonso, Ed., Remington's Pharmaceutical Sciences, 18^(th)Edition 1990, Mack Publishing Co., Easton, Pa., a standard referencetext in this field.

[0117] Pharmaceutically acceptable vehicles can be routinely selected inaccordance with the mode of administration and the solubility andstability of the compound. For example, formulations for intravenousadministration may include sterile aqueous solutions which may alsocontain buffers, diluents and other suitable additives.

[0118] Suitable formulations for parenteral administration includeaqueous solutions of the active compounds in water-soluble form, forexample, water-soluble salts. In addition, suspension of the activecompound as appropriate oily injections suspensions may be administered.Suitable lipophilic solvents or vehicles include fatty oils, forexample, sesame oil, or synthetic fatty acid esters, for example ethyloleate or triglycerides. Aqueous injection suspensions that may containsubstances which increase the viscosity of the suspension include, forexample, sodium carboxymethyl cellulose, sorbitol, and/or destran.Optionally, the suspension may also contain stabilizers.

[0119] Disorders or diseases associated with abnormal protein foldinginto amyloid or amyloid-like deposits or into pathologicalbeta-sheet-rich precursors of such deposits to be treated or preventedby administering the pharmaceutical composition of the inventionincludes, but is not limited to, Alzheimer's disease, FAF, Down'ssyndrome, other amyloidosis disorders, human prion diseases, such askuru, Creutzfeldt-Jakob Disease (CJD), Gerstmann-Strausslet-ScheinkerSyndrome (GSS), prion associated human neurodegenerative diseases aswell as animal prion diseases such as scrapie, spongiformencephalopathy, transmissible mink encephalopathy and chronic wastingdisease of mule deer and elk.

EXAMPLES

[0120] One of the major drawbacks for the use of peptides as drugs istheir rapid proteolytic degradation in biological fluids and tissues. Inin vitro experiments, iAβ5, (Seq LPFFD—also depicted as Leu Pro Phe PheAsp herein) degraded very quickly in vitro after incubation with freshhuman plasma. As shown in FIG. 4a, fifty percent of the peptide iAβ5disappeared in approximately 5 minutes in the presence of plasma. Sinceit was not possible to identify any metabolic fragments as a result ofthe proteolytic digestion, it seems likely that the degradation ismainly done by unspecific exopeptidases. This conclusion is supported bythe finding that protection of amino- and carboxy-terminus of thepeptide by acetylation and amidation, respectively, (to formAc-iAβ5-Am—also depicted as Ac-Leu Pro Phe Phe Asp-Am herein)dramatically increases the stability of the peptide in vitro. As shownin FIG. 4b, the end-protected modified peptide of the present invention(Ac-iAβ-Am) remained stable for a period of more than 24 hours in humanplasma. (The modified peptide was also slowly metabolized in vitro inhuman and rat liver microsomes, in which after one hour of incubation at37° a 81.5% and 76.3% of the peptide remained intact, in human and rattissue homogenate, respectively. )

[0121] Additional in vitro studies showed that Ac-iAβ5-Am has similaractivity as iAβ5 in inhibiting amyloid formation (see FIG. 5a) and theeffect followed a similar dose-dependency as the activity of theunmodified peptide as shown in FIGS. 5b and 5 c. Returning to FIG. 5a,it can be seen that modification of the N-terminus by Boc also retainsthe in vitro activity exhibited by iAβ5 while several unrelated peptides(CP1: VHVSEEGTEPA, CP2: GYLTVAAVFRG, CP10: ISEVKMDAEF) or short Aβfragments (such as Aβ18-21, Aβ1-16) at the same concentrations had noeffect on fibrillogenesis or slightly increased amyloid formationprobably by incorporation into the fibrils.

[0122] To evaluate the effect of Ac-iAβ5-Am in vivo, we used a rat modelin which amyloidosis was induced by intracerebral injection ofnon-aggregated Aβ1-42. After some time, the peptide aggregates insidethe rat brain resulting in the formation of a single amyloid-likedeposit in the place of injection. These lesions have the sametinctorial (congo red birefringence and thioflavine S binding) andtranslucent (fibrillar structure under electron microscopy) propertiesthan Alzheimer's amyloid plaques and induce some cerebral damage similarto that observed in AD brain, including extensive neuronal shrinkage,astrocytosis and microglial activation. Using this model, we have shownpreviously that co-injection of the unprotected iAβ5 with Aβ1-42 inducea 50% inhibition of amyloid plaque formation and i. c. injection of iAβ5in animals already containing amyloid plaques produced a 67% dissolutionof preformed deposits. (Sigurdsson, E. M., Permanne, B. Soto, C.,Wisniewski, T. & Frangione, B. (2000). In vivo disassembly of amyloid-βdeposits in rat brain. J. Neuropath. Exp. Neurol. 59: 11-17) In theprevious experiments, the unprotected peptide was injected directly inthe brain region where the amyloid was located. In the presentexperiment the amyloid-β5 peptide was injected into the amygdala of therats. After 7 days, which is the time required to have fully formed theamyloid deposits, one-hundred μL of a solution containing 13 mg/ml ofthe Ac-iAβ5-Am were infused for a period of three weeks using an ALZETinfusion pump connected to the lateral ventricle. The animals weresacrificed and the brain analyzed for the presence of amyloid depositsby immunohistochemistry. In this model, a compacted amyloid plaque wasobtained in the place where the solution containing Aβ1-42 was deposited(amygdala) and also several smaller amyloid deposits were observedthroughout the canula track in regions closer to the ventricle (FIG. 6,left panel). The results show that infusion of the peptide induces a 30%dissolution of preformed amyloid plaque in the amygdala and 83%dissolution of the deposits located near the ventricle (FIG. 6).

[0123] Experimental Procedures

[0124] In vitro assays of peptide stability. Peptides were prepared as a1 μg/μl solution in water. 20 μl of the peptide solution was diluted in80 μl of fresh human plasma. The solution was 15 incubated at 37° C. fordifferent time periods and the reaction was stopped by adding a completecocktail of protease inhibitors. The bulk of the plasma proteins (noneof the peptide) were precipitated in cold methanol (mix/MeOH, 4/5, v/v)for one hour at −20° C. The precipitated proteins were pelleted bycentrifugation (10 000 g, 10 min, 4° C.). The supernatant, containingthe peptide, was concentrated 5 times under vacuum and separated byreverse-phase HPLC. The peak area corresponding to the intact peptidewas measured and compared with an equivalent sample incubated withoutplasma.

[0125] In vitro assays of activity. Amyloid formation was quantitativelyevaluated by the fluorescence emission of thioflavine T (ThT) bound toamyloid fibrils. Aliquots of Aβ at a concentration of 0.5 mg/ml preparedin 0.1 M Tris, pH 7.4 were incubated for 7 days at 37° C. 5 in theabsence or in the presence of different concentrations of iAβ 5 andderivatives. At the end of the incubation period, 50 mM glycine, pH 9.2and 2 μM ThT were added in a final volume of 2 ml. Fluorescence wasmeasured at: excitation 435 nm and emission 485 nm in a Perkin Elmer,model LS50B fluorescence spectrometer.

[0126] In vivo studies using an animal model of cerebral Aβ deposition.Male Fischer-344 rats weighed 250-300 g and were 3-4 months of age atthe time of arrival. The animals were housed 2 per cage, maintained on a12 hour light-dark cycle with access to food and water ad libitum andwere habituated to their new environment for 2-3 weeks prior to surgery.Surgery was performed under sodium pentobarbital (50 mg/kg, i.p.)anesthesia. Atropine sulfate (0.4 mg/kg) and ampicillin sodium salt (50mg/kg) were injected subcutaneously once the animals were anesthetized.Aβ1-42 was dissolved in dimethylsulfoxide (DMSO) and then diluted withwater to a 16.7% DMS. The animal received a bilateral injection of 5.0nmol Aβ1-42 into each amygdala by using a Kopf stereotaxic instrumentwith the incisor bar set at 3.3 mm below the interaural line. Injectioncoordinates measured from the bregma and the surface of the skull(AP−3.0, ML±4.6 DV−8.8) were empirically determined based on the atlasof Paxinos and Watson. A volume of 3.0 μl was administered over 6 min(flow rate 0.5 μl/min) using a CMA/100 micrasyringe pump. The cannulawas left in situ for 2 min following injection, then it was withdrawn0.2 mm and left for 3 min, and after 5 min the cannula was slowlywithdrawn. Following surgery the animals were placed on a heating paduntil they regained their righting reflex. To evaluate the effect ofAc-iβ5-AM the animals were subjected to a second surgery one week afterthe first one, in which an ALZET infusion pump was connected to thecerebral ventricle following the manufacturer indications. A total of1.3 mg of peptide in 100 μL of PBS/10% DMSO was delivered into thelateral ventricle over a period of 3 weeks. After this time, the animalswere sacrificed by an overdose of sodium pentobarbital (150 mg/kg,i.p.), perfused transaortically. For histology, serial coronal sections(40 μm) of the brain were cut, placed in ethylene glycol cryoprotectantand stored at −20° C. until stained. Tissue sections were stained withanti Aβ1-42 antibodies as described in Soto, C., Sigursson, E., Morelli,L., Kumar, R. A., Castaifinõ, E. M. and Frangione, B.(1998) (β-sheetbreaker peptides inhibit fibrillogencsis in a rat brain model ofamyloidosis: Implications for Alzheimer's therapy. Nature med. 4:822-826. An image analysis system was used to determine the size of theamyloid deposits. The data was analyzed by a two-way ANOVA followed by aNewman-Keuls' multiple range test for post hoc comparisons. Total braindeposition was analyzed using an unpaired t-test, two tailed.

[0127] Having now fully described this invention, it will be appreciatedby those skilled in the art that the same can be performed within a widerange of equivalent parameters, concentrations, and conditions withoutdeparting from the spirit and scope of the invention and without dueexperimentation.

[0128] While this invention has been described in connection withspecific embodiments thereof, it will be understood that it is capableof further modifications. This application is intended to cover anyvariations, uses, or adaptations of the inventions following, ingeneral, the principles of the invention and including such departuresfrom the present disclosure as come within known or customary practicewithin the art to which the invention pertains and as may be applied tothe essential features hereinbefore set forth as follows in the scope ofthe appended claims.

[0129] All references cited herein, including journal articles orabstracts, published or corresponding U.S. or foreign patentapplications, issued U.S. or foreign patents, or any other references,are entirely incorporated by reference herein, including all data,tables, figures, and text presented in the cited references.Additionally, the entire contents of the references cited within thereferences cited herein are also entirely incorporated by reference.

[0130] Reference to known method steps, conventional methods steps,known methods or conventional methods is not in any way an admissionthat any aspect, description or embodiment of the present invention isdisclosed, taught or suggested in the relevant art.

[0131] The foregoing description of the specific embodiments will sofully reveal the general nature of the invention that others can, byapplying knowledge within the-skill of the art (including the contentsof the references cited herein), readily modify and/or adapt for variousapplications such specific embodiments, without undue experimentation,without departing from the general concept of the present invention.Therefore, such adaptations and modifications are intended to be withinthe meaning and range of equivalents of the disclosed embodiments, basedon the teaching and guidance presented herein. It is to be understoodthat the phraseology or terminology herein is for the purpose ofdescription and not of limitation, such that the terminology orphraseology of the present specification is to be interpreted by theskilled artisan in light of the teachings and guidance presented herein,in combination with the knowledge of one of ordinary skill in the art.

1 9 1 5 PRT Artificial Sequence Synthetic chemical peptide. 1 Leu ProPhe Phe Asp 1 5 2 13 PRT Artificial Sequence Synthetic chemical peptide.2 Asp Ala Pro Ala Ala Pro Ala Gly Pro Xaa Val Pro Val 1 5 10 3 5 PRTArtificial Sequence Synthetic chemical peptide. 3 Leu Xaa Phe Phe Asp 15 4 13 PRT Artificial Sequence Synthetic chemical peptide. 4 Asp Ala XaaAla Ala Xaa Ala Gly Xaa Ala Val Xaa Val 1 5 10 5 13 PRT ArtificialSequence Synthetic chemical peptide. 5 Asp Ala Xaa Ala Ala Xaa Ala GlyXaa Ala Val Pro Val 1 5 10 6 13 PRT Artificial Sequence Syntheticchemical peptide. 6 Xaa Ala Xaa Ala Ala Pro Ala Gly Xaa Ala Val Pro Val1 5 10 7 13 PRT Artificial Sequence Synthetic chemical peptide. 7 AspAla Xaa Ala Ala Pro Ala Gly Xaa Ala Val Pro Val 1 5 10 8 13 PRTArtificial Sequence Synthetic chemical peptide. 8 Asp Ala Xaa Ala XaaXaa Ala Xaa Xaa Ala Val Pro Val 1 5 10 9 11 PRT Artificial SequenceSynthetic chemical peptide. 9 Arg Asp Leu Pro Phe Tyr Pro Val Pro IleAsp 1 5 10

What is claimed is:
 1. An inhibitory peptide capable of inhibiting βpleated sheet formation in amyloid β-peptide said inhibitory peptidebeing a βsheet breaker peptide analog designed by chemical modificationof a βsheet breaker peptide capable of inhibiting β pleated sheetformation in amyloid β-peptide.
 2. The inhibitory peptide of claim 1wherein said βsheet breaker peptide is a 5 residue Alzheimer inhibitorpeptide iAβ5 (Leu-Pro-Phe-Phe-Asp SEQ ID NO: 1).
 3. An inhibitorypeptide capable of inhibiting conformational changes in prion PrPprotein associated with amyloidosis, said inhibitory peptide being aβsheet breaker peptide analog designed by chemical modification of aβsheet breaker peptide capable inhibiting said conformational changes inprior PrP protein associated with amyloidosis.
 4. The inhibitory peptideof claim 3 wherein said βsheet breaker peptide is 13 residue prioninhibitor peptide iPrP 13 (Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala ValPro Val, SEQ ID NO: 2).
 5. The inhibitory peptide of claim 4 whereinsaid chemical modification is achieved by a process selected from thegroup consisting of: alteration of the N- and C-terminal ends of saidprion inhibitor peptide iPrP13; replacing at least one residue of saidprion inhibitor peptide iPrP13with α-aminoisobuiric acid (Aib);methylation of the α carbon of at least one residue of said prioninhibitor peptide iPrP13; replacing at least one L-enantiomeric residueof said prion inhibitor peptide iPrP13 with a D-enantiomeric residue,forming head-to-tail cyclization of said prion inhibitor peptide iPrP13,replacing amide bonds in said prion inhibitor peptide IPrP13 with anamide bond surrogate; and combinations thereof.
 6. The inhibitorypeptide of claim 5 wherein said alteration of the N- and C-terminal endsof said prion inhibitor peptide iPrP13 is achieved by a process selectedfrom acetylation, amidation, desamination, alcoholization andcombinations thereof.
 7. The compound of claim 6 wherein said inhibitorypeptide is selected from the group consisting of: ac-Asp Ala Pro Ala AlaPro Ala Gly Pro Ala Val Pro Val-am, des-Asp Ala Pro Ala Ala Pro Ala GlyPro Ala Val Pro Val-am, ac-Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala ValPro Val-alc, and des-Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala Val ProVal-alc.
 8. The inhibitory peptide of claim 5 wherein said inhibitorypeptide is selected from the group consisting of Asp Ala Aib Ala Ala AibAla Gly Aib Ala Val Aib Val (SEQ ID NO: 4); Asp Ala Pro Ala Ala Pro AlaGly Pro Ala (Me)Val Pro Val; Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala ValPro (Me)Val; Asp Ala Pro Ala Ala Pro Ala Gly Pro Ala (Me)Val Pro(Me)Val; asp ala pro ala ala pro ala gly pro ala val pro val; asp AlaPro Ala Ala Pro Ala Gly Pro Ala Val Pro val; asp Ala Pro ala Ala Pro alaGly Pro ala Val Pro val; Aspψ[CH₂CH₂]Ala Proψ[CH₂CH₂]Ala AlaProψ[CH₂CH₂]Ala Gly Proψ[CH ₂CH₂]Ala Val Proψ[CH₂CH₂]Val; Aspψ[CH₂S]AlaProψ[CH₂S]Ala Ala Proψ[CH₂S]Ala Gly Proψ[CH₂S]Ala Val Proψ[CH₂S]Val;Ac-Asp Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala Gly Proψ[CH₂CH₂]Ala ValPro Val-Am; asp Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala GlyProψ[CH₂CH₂]Ala Val Pro val; Ac-Asp Ala Proψ[CH₂S]Ala Ala Proψ[CH₂S]AlaGly Proψ[CH₂S]Ala Val Pro Val-Am; asp Ala Proψ[CH₂S]Ala AlaProψ[CH₂S]Ala Gly Proψ[CH₂S]Ala Val Pro val; Ac-Asp Ala Aib Ala Ala AibAla Gly Aib Ala Val Pro Val-Am (SEQ ID NO: 5); Ac-Asp AlaProψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala Gly Proψ[CH₂CH₂]Ala Val Pro (Me)Val;Ac-Asp Ala pro Ala Ala Proψ[CH₂CH₂]Ala Gly pro Ala Val Pro Val-Am; aspAla Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala Gly Proψ[CH₂CH₂]Ala Val Pro(Me)Val; asp Ala Aib Ala Ala Proψ[CH₂CH₂]Ala Gly pro Ala Val Pro (Me)Val(SEQ ID NO: 6); asp Ala Aib Ala Ala Proψ[CH₂S]Ala Gly pro Ala Val Pro(Me)Val; asp Ala Proψ[CH₂S]Ala Ala Proψ[CH₂S]Ala Gly Proψ[CH₂S]Ala ValPro (Me)Val; Ac-Asp Ala Aib Ala Ala Proψ[CH₂CH₂]Ala Gly Aib Ala Val Pro(Me)Val (SEQ ID NO: 7);

Ac-Asp Ala Proψ[CH₂S]Ala ala Proψ[CH₂S]Ala gly Proψ[CH₂S]Ala (Me)Val ProVal-Am; Ac-Asp Ala Aib ala Ala Proψ[CH₂CH₂]Ala Gly pro Ala Val Pro(Me)Val; asp Ala Aib Ala Ala Proψ[CH₂CH₂]Ala Gly Aib ala Val Pro Val-Am;Ac-Asp Ala pro Ala Ala Proψ[CH₂CH₂]Ala gly pro Ala (Me)Val Pro Val-Am;asp Ala Proψ[CH₂CH₂]Ala Ala Proψ[CH₂CH₂]Ala gly Proψ[CH₂CH₂]Ala val Proval; Ac-Asp Ala pro Ala ala Aib Ala gly pro Ala (Me)Val Pro Val-Am (SEQID NO: 8); Asp Ala pro Ala Ala Proψ[CH₂CH₂]Ala Gly pro Ala Val Pro Val;Asp Ala Aib Ala Ala Proψ[CH₂CH₂]Ala Gly Aib Ala (Me) Val Pro Val; and,


9. A peptide mimetic with the following structure:


10. A peptide mimetic with the following structure:


11. A peptide mimetic with the following structure:


12. A method for reducing the formation of amyloid or amyloid likedeposits involving abnormal folding into β sheet structure of amyloid βpeptide or for reducing the amount of said amyloid β peptide which hasalready formed into a beta sheet structure comprising bringing into thepresence of said amyloid β peptide either prior to or after the abnormalfolding thereof into a β sheet structure, an effective amount of thepeptide of claim
 1. 13. A method for reducing the formation of amyloidor amyloid like deposits involving conformational changes in prion Prprotein or reducing the amount of said prion Pr protein which hasalready formed into amyloid or amyloid-like deposits comprising bringinginto the presence of said peon Pr protein either prior to or after saidconformational changes thereof into amyloid deposits an effective amountof the peptide of claim
 3. 14. A method for reducing the formation ofamyloid or amyloid like deposits by administration of a peptide mimeticselected from one of the group consisting of: